Sorry but it's your lineup which is a nonsense. Ackerman is the first substitute as SG and C, and because you use stricktly follow depth chart, the game engine will use him as SG or C, no other position. But Ackerman is a C so I suppose he's much better as C and so the GE uses him as C for the last quarter, when all the substitutes have to play.
But Tsunami can't play as C since the GE allready chooses Ackerman, and you don't give any indication for another position. So the GE uses Tsumani at his best position: SF. That couldn't be more logical.
That part make sense, but it doesn't explain why Okamura played at center - it would have made more sense for one of the players listed there to swap over to that position and then Okamura play at his position. Of course, when there are only two substitute players and the game gets into garbage time, and the depth chart is as colorful as this one is, who knows what is going to happen?
The one thing I will say is that conventional wisdom has held that to get a guy 48 minutes, everyone else on the depth chart should either be a starter or backup, and not just a reserve only. My assumption is that it's a fairly known phenomenon that someone who is fielded as only a reserve will be played in whatever position can relieve a starter. I would imagine (though I have no way of knowing) that if Tsunami had been the backup C, he would have been played there exclusively, and then Okamura could have been brought back in to relieve other positions but wouldn't replace Tsunami at C.